1. Field of the Invention
The present invention relates to a method and device for wavelength conversion, and a system including the device.
2. Description of the Related Art
As a technique for increasing a transmission capacity by a single optical fiber, wavelength division multiplexing (WDM) is known. In a system adopting WDM, a plurality of optical carriers having different wavelengths are used. The plural optical carriers are individually modulated to thereby obtain a plurality of optical signals, which are wavelength division multiplexed by an optical multiplexer to obtain WDM signal light, which is output to an optical fiber transmission line. On the receiving side, the WDM signal light received is separated into individual optical signals by an optical demultiplexer, and transmitted data is reproduced according to each optical signal. Accordingly, by applying WDM, the transmission capacity in a single optical fiber can be increased according to the number of WDM channels.
It is now being considered to construct a wide-area photonic network in the future by connecting WDM systems, and the development of a node configuration or an optical cross-connect (OXC) device required for such a photonic network is being pursued. The node is provided by an optical add/drop multiplexer (OADM) for extracting (dropping) an optical signal from a network and inserting (adding) an optical signal into the network. The optical cross-connect device is used to switch the paths of optical signals.
It is considered that direct connection of largely demanded IP packet information to a photonic network without through a current SONET/SDH device or ATM device will become a mainstream (IP over WDM). Accordingly, a wavelength converter for converting the wavelength of an optical signal is one of the key technologies for realization of such a photonic network.
Conventionally, research has been made on a method for wavelength conversion by generation of four-wave mixing with a semiconductor optical amplifier or a DFB laser.
However, the conventional method for wavelength conversion has a problem such that the efficiency of generation of converted light after wavelength conversion is very low. Further, a conventional device for wavelength conversion requires control light for generating four-wave mixing, causing a complicated configuration.